The 38-year-old comedienne says she is suffering from the same stage fright that blighted her schooldays.
"I have always been outgoing in some ways but if I had to speak in front of the class, I would not go to school that day," says Kristen.
"I would get sick to my stomach. Even now I would not be able to do it. It is different when you are yourself talking to people but when you are acting, it is easier."